hmmwv15

I was heading down a rough hill, and began to slide due to a previous rain. This hill you can't go down too fast or you'll break stuff. I naturally put full pressure to my brakes, and 1/2 way down heard a pop and my brakes were all the sudden spongy. Got to the bottom, crawled through the mud checked all the lines. Nothing leaking. Popped the hood and my fluid was still between min and max. pumped the brakes, fluid's still there. Was on my way home and did a brake check and they still stop the truck. Only problem is the pedal is almost touching the floor. Can I drive it tomorrow? Is it safe? I'm thinking about bleeding them and seeing if that helps. Anyone know what's up?

86SR522REEFI

check your wheel cylinders and your brake lines, also check to see if your master is leaking. You have to remove the drums to check the wheel cylinders

hmmwv15

Master isn't leaking, but do you think I could get away with driving it about 20-30 miles and then check it? That's a round trip to school and back. I really can't afford to miss school, but if you think it's not safe I guess I'll have to be late...

drguitarum2005

could be a hole on the inside of your master. happened to me on my isuzu once, the cylinder "plunger" was just bypassing the fluid so while nothing was leaking, the MC had no compression

hmmwv15

So even though I still have pressure it could be a hole? I still need to know if I can drive it tomorrow...

drguitarum2005

could be a small hole. if you hold your brakes while on a hill or something, will it eventually hit the floor and even after that your brakes start to let up?

hmmwv15

What? Not sure I understand what your trying to say, but I'm still able to stop the truck reasonably fast. I just come too close to the floor and for me that's a bit too close for comfort. Not sure if it's a ticking time bomb that will lead to total brake failure or not, but I just don't have the time to troubleshoot right now, and I don't have time in the morning either. So I need to know if I can drive it or not.

drguitarum2005

if youre sitting somewhere stopped with your brakes (on a hill), will the pedal eventually hit the floor to keep you stopped? when i say that, i mean does your pedal slowly move more toward the floor to keep your breaks engaged? if so, that would imply a hole somewhere in the cylinder most likely.

as with any brake problem youre taking a major risk driving it. no one can tell you if its safe or not without inspecting it, so do it at your own risk. be ready with the ebrake if you do drive it like that though

hmmwv15

No the pedal still stops firmly, it just seems like air somehow got into the system and then closed back up. Really odd, but it just makes me nervous. I guess I'll just be ready on the e-brake like I was on the way home and as you mentioned. I just hope I don't get behind an idiot on the way to school...

longhungsilver

be careful, cant say either way wether you will have a brake failure or not.. sounds very much like a master cylinder problem... make sure you look into it even if bleeding helps theres got to be a reason air got in, in the first place.. so make sure u dont not look into it... check wheel cylinders and pistons... double check all lines and if none of those turn out to be the problem its probably your master...

take a look at the ground where your brake pedal is.. look up and see if u see any brake fluid on the linkage at the firewall. if so the rear seal in the master is going

hmmwv15

I don't think it's the master, I just replaced it about a month or two ago. I'll check everything tomorrow before I go, and I assure you all, I have checked everything I possibly could without taking anything apart. I guess I will check the whole system after school tomorrow. I might just ask my dad about borrowing the explorer.

jcfb

The soft lines going from the hard line to the caliper on the front (since the front does about 70% or more of the braking) are dual wall. What can happen on old lines is with a sudden application of full force braking, the inner line will burst, letting fluid into the outer line. So while you still get braking, the pedal can put more fluid into the line, which accounts for the low pedal, but still braking ability. I would get under the truck and watch the lines as someone in the truck presses on the brakes. If the inner line is burst, you will probably see the outer line bulge a little. It's a common problem, especially on old brake lines. This most likely wouldn't cause a leak either, so you'd still have full fluids.

longhungsilver

very probable actually.... take a look at your lines and see.. also rubber soft lines collapse internally which could create a squissy peddle.... take your tires off the front and see how hard the rotor is to turn. (in 2wd).. it shouldnt be to hard at all should spin relatively freely.. if its stuck your caliper is seized or you have a collapsed break line... crack the bleeder while sumone holds the breaks and if the problem is resolved it is your lines and if it is not then its the caliper.....

hmmwv15

Upon bleeding, I noticed a squeak sound when somone pushes on the brake pedal. There was air in all four lines, and we got that out, all lines bled, got in pushed the brake and their still spongy. I think I'm going to check on those brake lines and see if the inner wall is busted.

hmmwv15

This is turning into one pita brake problem. I replaced the brake booster because I called a very trustworthy auto mechanic I know, and he said it was probably the booster. I snatch the one off of the 2wd and it still has the same problem. Now there is an annoying squeaking noise comming from the driver side rear wheel area. The ###### thing is mocking me. I guess I'll bleed the brakes yet again tomorrow, and troubleshoot from there. I effing hate this.

hmmwv15

Looks like autozone likes to give me bad master cylinders....We took the old one back and naturally they replaced it. Now the one they replaced it with doesn't want to bleed properly. I think they just lost a customer...

jcfb

Did you bench bleed the MC?

hmmwv15

Yes, but we have since gotten a new one, and found out that's not the problem. We installed the new MC and began to bleed everything. The wheel cylinder started visibly leaking after we vigorously started bleeding the entire system. Now we just need to replace EVERYTHING inthe wheel after we saw that there was n't ANY pad left on the shoe. Looks like I just ran into a case where the previous owner(s) NEVER serviced the rear brakes. I can't believe they held for this long. So I guess it will be a full rear brake system overhaul.

hmmwv15

If your underneath the truck looking at the little gear inside the wheel (behind the rubber stopper and under the brake line that is under the bleeder valve.) which way do you turn the gear. (up or down) There are slanted gears on it like this: /l/l/l/l all the way around.

hmmwv15

Like this:


The gear in the middle of the hole. Turn it up or down?